Tag Archives: English

Long time no blog. Sorry about that. Things have gotten a bit busy since I changed jobs in Nov 2013, moving along to the crazy and sometimes insane world of automotive in general and IVI in special. Due to that and a rather unpleasant commute, things in Rygel land have gotten a tad more silent then I hoped, not revolutionary, maybe not even evolutionary. For example, there’s still no ACL support as I promised way back on GNOME.Asia 2013.

I will have to skip FOSDEM this year for several reasons, sorry about that.

For Rygel, I hope to finish the integration of (most of) Cablelab’s changes for their CVP-2 work as they will allow nice and long requested features such as pre-transcoding or transcode caching, server-side trickmodes, simple device-dependent resource reorder (for devices that are too stupid to pick the proper resource). Unfortunately I have found a rather large feature regression with upload that seems to turn out to be somewhat nasty to fix.

I’m currently working on adding DVD sharing to Rygel and while doing that, I resurrected a tool I wrote in 2005 to aid the tedious process of authoring DVDs on Linux. Today I cleaned it up a bit, gitified it and pushed it to github: https://github.com/phako/authorg

Please be warned that it might kill your data if you don’t read the message boxes carefully and cancel in time (and I mean that seriously, not as a standard disclaimer).

TL;DR:

What’s this problem?

There are already several solutions in the wild that combine Rygel and the Rasbperry Pi, be it Guacamayo or stock Raspbian. While Guacamayo provides easy server and audio renderer images, none of the existing solutions provide a video renderer.

Why’s that? Well, the RPi is (intentionally) slightly underpowered to do video decoding on the CPU. Howerver, it supports video decoding in hardware.

The issue here is that Raspbian is based on wheezy which only comes with GStreamer 0.10 while the support for hardware-based video decoding on the RPi in gstreamer-omx was only added recently to GStreamer 1.0.x. And since this is wheezy, the Rygel package that comes with it is too old to use GStreamer 1.0.

So let’s just grab the packages from sid armhf, should be working, no?

No it doesn’t. Rasbpian is basically a recompilation of Debian for ARMv5 with hard float ABI, while Debian itself is using ARMv7. So we can’t just copy packages.

And what exactly are you doing now?

We provide a Debian repository with Rygel’s packages backported to Raspbian. That’s a bit boring, you say? Indeed. This is only the beginning. There will also be a set of instructions to convert a Rasbian installation into a hardware-accelerated DLNA renderer. The first step to this is a meta-package called raspbian-dlna-renderer which depends on all the other important packages necessary for a complete environment.

A bit late for the “I’m back from this year’s GNOME.Asia” post, but well. This was the fist GNOME.Asia event I attended and even my first time in asia and it was a very interesting experience that needs repeating. It was nice to meet all those people from around this part of the world who never make it to the european conference and I was particularly pleased to meet Jiro who enabled i18n support in the GUPnP tools and to learn about the <Super>M shortcut to get the message bar. Unfortunately I couldn’t join the city tour on Sunday since I was already heading back to London then.

I did a talk on DLNA (who would have guessed that) in GNOME and some of the things that might come: Slides of the talk. I’m afraid the blog post on setting up a hardware-accelerated DLNA renderer on the Raspberry Pi that I announced during the talk is still not written, sorry about that.

A big thanks to the the cheerful local team, the GNOME.Asia people and of course the sponsors who made all this possible and thanks to the GNOME foundation for sponsoring my attendence.

While we were busy fixing the server and rendering side of DLNA with Rygel, the guys at Intel OTC are fixing the Client side of DLNA with something called dLeyna, a nice set of APIs to access and maipulate UPnP-AV and DLNA servers / renderers (such as Rygel, of course), so you can easily add DLNA support to your applications, including the obvious server browsing and render remote control, but also the more non-obvious like media pushing, synchronization, server-side playlists. They already prepared a cool set of demos (for example a Firefox extension to send images from your browser to your TV).

So why is this better than using GUPnP for this? Let me show you some examples.

Controlling a renderer

Not much code to see here, you get the usual suspects of player control functions such as start, stop, etc. as well as methods to query device’s capabilities as there are a lot of optional things on UPnP devices.

Behind the scenes, this is all GUPnP of course. Currently it consists of two DBus services, dleyna-renderer-service and dleyna-server-service, although other IPC mechanisms are on its way. What happens is that that these two services scan the network for available devices and making them available through a set of DBus interfaces, relieving you from the need of searching for devices yourself (and with that providing a device cache, relieving the network from UDP packet bursts), introspecting the devices for supported capabilities and methods and so on.

If you execute the push script from above you get a python wrapper for the com.intel.dLeynaRenderer.Manager DBus interface, which is then locally looking for the DBus path matching the given UPnP UDN and returning a python object implementing the com.intel.dLeynaRenderer.PushHost and com.intel.dLeynaRenderer.RendererDevice interfaces.

Then we temporarily host the file given on the command-line on dLeyna’s internal HTTP server, stopping the currently running playback (Which translates to RenderingControl:Stop SOAP call), send the URI to the server (RenderingControl:SetAVTransportURI) and last but not least start the playback (RenderingControl:Play) which in the end starts the HTTP streaming from dleyna’s internal HTTP server to (Rygel’s) renderer.

And it doesn’t stop at the application level, there’s even integration with HTML5 through cloudeebus and cloud-dLeyna.

As a sidenote: You might ask how that relates to Grilo’s UPnP-AV support or Korva. This is a very valid question. Grilo and Korva are doing very specific tasks while dLeyna aims to be a more complete SDK. It should be quite easy, for example, to port Grilo’s UPnP-AV suppport to dLeyna.

It’s been a while since I last blogged about Rygel. Many things have happened since, mainly in features and documentation.

Features

Exchangeable media engines: We’ve loosened the dependency on GStreamer a bit. While it is still our first-class transcoding and general media handling library, it is now possible to substitute it with other media processing libraries. A simple example is included in the source.

Change tracking. This is a feature introduced in the UPnP content directory specification version 3. It allows clients to, well, track the changes that happen on the server in detail for synchronization purposes. It’s implemented in the framework and as a demonstration in the MediaExport plug-in.

GStreamer 1.0 support. As the rest of GNOME, we transitioned to GStreamer 1.0.

Playlist support. Rygel now generates playlists for containers on-the-fly and the renderer framework supports automatic playback of them. The only format that’s supported currently is one of the two formats defined by DLNA, DIDL_S, which is just the same format that is used by UPnP AV to describe the media content on a server.

Playspeed support. A renderer now can announce that it supports different speeds and directions than normal forward playback.

API

There was another split-up into a renderer framework library and a specific implementation of a renderer using GStreamer which again may be used in your own programs. This is mainly due to the aforementioned change in media backend flexibility.

Otherwise we’re working on making the API easier to use from C and other languages through introspection.

Documentation

There’s been a lot of effort into extending our sparse documentation. It is currently concentrating on the APIsideofthings but will be extended to a higher level as well soon.

Misc

There is an example now that implements a DLNA renderer which is running in full-screen

There are several examples for the most common init systems to run Rygel as a system service if wanted

Helium 0.6.0 is available. It mostly contains back-end changes, but several user-visible changes as well:

Improved seeking

The handling of seeking in the player view has been improved. The area that reacts to the
seeking has been enlarged and the the flicking doesn’t steal the events anymore. A tool-tip will show the current seek position.

Filtering

It is now possible to filter the list of media files. To activate the filter input, just drag down and pull the list at the top as in every other program on the device. By default the filtering will only work on the titles. This can be changed in settings to match against most of the other meta-data as well.

Debugging

It’s now possible to log the UPnP traffic to help debugging of interoperability issues. By default, the log file is written to MyDocs to enable easy transfer of the log files via mass storage mode.